結果

問題 No.2717 Sum of Subarray of Subsequence
ユーザー pitP
提出日時 2024-04-05 22:31:37
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 74 ms / 2,000 ms
コード長 3,183 bytes
コンパイル時間 3,872 ms
コンパイル使用メモリ 255,100 KB
最終ジャッジ日時 2025-02-20 21:45:31
ジャッジサーバーID
（参考情報） 		judge2 / judge1
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 21
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
istream &operator>>(istream &is, modint &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint &a) { return os << a.val(); }
istream &operator>>(istream &is, modint998244353 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint998244353 &a) { return os << a.val(); }
istream &operator>>(istream &is, modint1000000007 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint1000000007 &a) { return os << a.val(); } 
typedef long long ll;
typedef vector<vector<int>> Graph;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define FOR(i,l,r) for (int i = l;i < (int)(r); i++)
#define rep(i,n) for (int i = 0;i < (int)(n); i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define my_sort(x) sort(x.begin(), x.end())
#define my_max(x) *max_element(all(x))
#define my_min(x) *min_element(all(x))
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int INF = (1<<30) - 1;
const ll LINF = (1LL<<62) - 1;
const double PI = acos(-1);
vector<int> di = {1,0,-1,0};
vector<int> dj = {0,1,0,-1};
#ifdef LOCAL
#  include <debug_print.hpp>
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif
//https://drken1215.hatenablog.com/entry/2018/06/08/210000
//COMinit()を忘れない!!!
const ll NMAX = 202020;
const ll MOD = 998244353;
//const int MOD = 1e9+7;
ll fac[NMAX],finv[NMAX],inv[NMAX];
void COMinit(){
    fac[0] = fac[1] = 1LL;
    finv[0] = finv[1] = 1LL;
    inv[1] = 1LL;
    for (int i=2;i<NMAX;i++){
        fac[i] = fac[i-1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD/i) % MOD;
        finv[i] = finv[i-1] * inv[i] % MOD;
    }
}
ll nCr(int n,int k){
    if (n<k) return 0LL;
    if (n < 0 || k < 0) return 0LL;
    return fac[n] * (finv[k] * finv[n-k] % MOD) % MOD;
}
ll nPr(int n,int k){
    if (n<k) return 0LL;
    if (n < 0 || k < 0) return 0LL;
    return fac[n] * finv[n-k] % MOD;
}
ll nHr(int n,int r){
    return nCr(n+r-1,r);
}
using mint = modint998244353;
int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    COMinit();
    int N; cin >> N;
    vector<mint> A(N);
    rep(i,N) cin >> A[i];
    
    mint ans = 0;
    if(N <= 3){
        for(int i = 0; i < N; i++){
            for(int l = 0; l <= i; l++){
                for(int r = 0; r <= N - i - 1; r++){
                    mint tmp = A[i];
                    tmp *= l + 1;
                    tmp *= r + 1;
                    tmp *= nCr(i, l);
                    tmp *= nCr(N - i - 1, r);
                    ans += tmp;
                    debug(i, l, r, tmp);
                }
            }
        }
    }
    else{
        for(int i = 0; i < N; i++){
            mint tmp = A[i];
            tmp *= (i + 2) * (-mint(2).pow(N - 3)) * (i - N - 1);
            ans += tmp;
        }
    }
    cout << ans << endl;
}
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